Safety

Practicalities Getting Organised Safety Mobile Phones 

This can be invaluable when you need to sort out a problem on the spot. However, if you plan to take one you need to check whether it works at your destination. Mobiles are not particularly common in the US for example and most European models won't work there but even in Europe you may encounter problems unless you have paid extra for overseas access.

You may need to call your phone company to check how they make the changes for certain countries and how much they charge for this. Alternatively you may want to hire a tri-band which works worldwide.

Note however that calls made overseas, even locally, are horrendously expensive so use should be limited to genuine need unless you have a large budget.